Field
The present specification generally relates to pulling rolls for use in the manufacture of sheet glass in a glass manufacturing process.
Technical Background
Pulling rolls are used in the manufacture of sheet glass to apply a vertical pulling force to a ribbon or web of glass from which individual sheets are formed. The amount of pulling force applied by the pulling rolls to the glass is utilized to control the nominal thickness of the glass as the glass is drawn from molten glass, such as in an overflow downdraw fusion process, as described in U.S. Pat. Nos. 3,338,696 and 3,682,609, or a similar process. In addition to a main pulling roll, additional rolls are sometimes used in ribbon drawing processes to stabilize ribbon motion, or to create horizontal tension across the glass ribbon. Though generically referred to as pulling rolls, these rolls can sometimes be run without drive motors so that the rolls rotate through the contact with the moving glass ribbon. Whether actively driven or passively driven, rolls which contact the ribbon during the drawing process are referred to as pulling rolls.
When pulling rolls are used to draw molten glass, the relatively high temperature of the molten glass may cause the portion of the pulling roll in contact with the molten glass to degrade. Over time, the pulling roll and/or the portion of the pulling roll in contact with the molten glass must be replaced, causing process down time and increased manufacturing costs.
Accordingly, alternative pulling roll designs are needed.